I speculate that economic conventional wisdom says, "discount sooner in poorer market conditions." If I were to make a gross linear interpolation based on the recent 69% profit loss figure (which I will disgustingly use instead as a percentage change in units-sold) and your 2 week number, and assuming that Nokia wants to sell the same number of units before the RX-51 release, 6 1/2 weeks would be the earliest. But if the trend is that conditions are worsening, it would be longer. YMMV

number_of_weeks = 2 / (100% - 69%)